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CN-122025573-A - High-capacity high-nickel ternary positive electrode material and preparation method thereof

CN122025573ACN 122025573 ACN122025573 ACN 122025573ACN-122025573-A

Abstract

The invention discloses a high-capacity high-nickel ternary cathode material and a preparation method thereof, belonging to the technical field of lithium ion battery electrode materials, wherein the preparation method comprises the steps of preparing a nickel-cobalt binary precursor, performing pre-oxidation treatment, and coating manganese salt to form a ternary precursor with a core-shell structure; the preparation method comprises the steps of carrying out heat treatment in a reducing atmosphere, uniformly mixing the heat treated material with nano-scale composite doping agents containing titanium, antimony and tantalum, carrying out four-section temperature programming sintering to obtain a high-nickel ternary anode substrate, realizing gradient coating of gradual change of Al/Ti molar ratio through dynamic flow control, and carrying out drying, medium-temperature heat treatment, crushing, sieving and demagnetizing to obtain the high-capacity high-nickel ternary anode material. The preparation method effectively solves the technical problems of insufficient doping uniformity, unsmooth combination of the coating layer and the matrix and the like of the existing high-nickel ternary positive electrode material through multi-step collaborative design, and the obtained material has high specific capacity, excellent cycle stability and thermal safety, low interface impedance and excellent processability, and is suitable for preparing the lithium ion battery with high energy density.

Inventors

  • FAN ZHAOFENG
  • YANG XIN
  • Fu Qingpan

Assignees

  • 扬州虹途电子材料有限公司

Dates

Publication Date
20260512
Application Date
20260105

Claims (10)

  1. 1. The preparation method of the high-capacity high-nickel ternary cathode material is characterized by comprising the following steps of: S1, adding a nickel-cobalt mixed salt solution, a sodium hydroxide solution and an ammonia water solution into water to prepare a nickel-cobalt binary precursor, adding the nickel-cobalt binary precursor into water, introducing compressed air to perform pre-oxidation treatment, and adding a manganese salt solution and an ammonia water solution into a reaction system to prepare a high nickel ternary precursor with a core-shell structure; S2, carrying out solid-liquid separation, washing and drying on the high-nickel ternary precursor, and carrying out surface reduction heat treatment in a hydrogen/nitrogen mixed atmosphere; S3, mixing the precursor subjected to the surface reduction heat treatment in the step S2 with a doping agent, wherein the doping agent is a compound of a titanium source, an antimony source and a tantalum source; s4, mixing the precursor doped in the step S3 with a lithium source, and performing sectional sintering treatment in an oxygen atmosphere to obtain a high-nickel ternary anode matrix material; S5, dispersing the matrix material in absolute ethyl alcohol to form slurry, adding a mixed coating agent solution consisting of a titanium source solution and an aluminum source solution into the slurry for gradient coating treatment to form an Al-Ti-O gradient coating layer; S6, carrying out solid-liquid separation, washing and drying on the coating product obtained in the step S5, carrying out heat treatment in an oxygen atmosphere, and obtaining the high-capacity high-nickel ternary anode material after crushing, sieving and demagnetizing.
  2. 2. The preparation method of the high-capacity high-nickel ternary cathode material according to claim 1, wherein in the step S1, the nickel salt is selected from at least one of nickel sulfate, nickel nitrate or nickel acetate, the cobalt salt is selected from at least one of cobalt sulfate, cobalt nitrate or cobalt acetate, and the manganese salt is selected from at least one of manganese sulfate, manganese nitrate or manganese acetate; The concentration of the nickel-cobalt mixed salt solution and the manganese salt solution is 0.8-1.2mol/L; The concentration of the sodium hydroxide solution is 5-10mol/L, and the concentration of the ammonia water solution is 8-12mol/L.
  3. 3. The preparation method of the high-capacity high-nickel ternary cathode material according to claim 1, wherein in the step S1, the pH value of the prepared nickel-cobalt binary precursor is 10.0-12.0, the reaction temperature is 50-70 ℃, the stirring rotation speed is 600-1000rpm, and the reaction time is 5-60h; The pre-oxidation treatment is carried out, the gas flow of the compressed air is 80-100L/h, the treatment temperature is 90-100 ℃, and the treatment time is 10-20min; the pH value of the high-nickel ternary precursor is 8.0-10.0, and the reaction time is 2-6h.
  4. 4. The preparation method of the high-capacity high-nickel ternary cathode material according to claim 1, wherein in the step S2, the total gas flow of the mixed atmosphere is 2-5L/min, the hydrogen volume fraction is 3-8%, the heat treatment temperature is 280-350 ℃, and the heat preservation time is 1-3h.
  5. 5. The method of preparing a high-capacity high-nickel ternary cathode material according to claim 1, wherein in the step S3, the titanium source is at least one selected from titanium dioxide, tetrabutyl titanate and titanyl sulfate, the antimony source is at least one selected from antimony trioxide, antimony pentoxide and antimony acetate, and the tantalum source is at least one selected from tantalum pentoxide, lithium tantalate and tantalum oxalate; The mass percentage ranges of the three doped metal elements of titanium, antimony and tantalum are respectively 800-3000ppm of titanium, 1500-5500ppm of antimony and 1500-5500ppm of tantalum by taking the precursor subjected to surface reduction heat treatment as a reference.
  6. 6. The method for preparing the high-capacity high-nickel ternary cathode material according to claim 1, wherein in the step S4, the lithium source is lithium hydroxide or lithium carbonate, and the molar ratio of the precursor to the lithium source is 1:1.05-1.10; the oxygen flow in the sectional sintering process is 5-10L/min, and specifically comprises the following steps: Heating to 480-520 ℃ at 3-5 ℃ per min for 1-3h, heating to 630-670 ℃ at 2-4 ℃ per min for 4-6h, heating to 700-740 ℃ at 1-3 ℃ per min for 7-9h, and cooling to 580-620 ℃ at 2-4 ℃ for 5-7h.
  7. 7. The method of claim 1, wherein in the step S5, the aluminum source solution is 0.1-0.3mol/L aluminum isopropoxide ethanol solution, and the titanium source solution is 0.05-0.2mol/L tetrabutyl titanate ethanol solution.
  8. 8. The method of claim 1, wherein in step S5, the molar ratio of aluminum to titanium in the mixed coating agent solution is linearly graded from 1:0.1 at the beginning to 1:0.9 at the end, the pH value is 8.5-9.5, and the total coating time is 1-2h.
  9. 9. The method for preparing the high-capacity high-nickel ternary cathode material according to claim 1, wherein in the step S6, the heating rate of the heat treatment is 2-4 ℃ per minute, the treatment temperature is 300-400 ℃, and the treatment time is 4-8 hours.
  10. 10. The high-capacity high-nickel ternary cathode material prepared by the preparation method of any one of claims 1-8 is characterized by having a chemical formula of LiNi x Co y Mn z O 2 @Al 1-a Ti a O m , wherein x is 0.80-0.95, y is 0.05-0.15, z is 0.02-0.08, a is linearly increased from 0.09 to 0.47 along the thickness direction of the gradient coating layer, and the total thickness of the gradient coating layer is 8-25nm.

Description

High-capacity high-nickel ternary positive electrode material and preparation method thereof Technical Field The invention relates to the technical field of lithium ion battery electrode materials, in particular to a high-capacity high-nickel ternary positive electrode material and a preparation method thereof. Background Along with the rapid development of new energy industry, the demand of the lithium ion battery for energy density is continuously improved, and the high-nickel ternary cathode material (Ni content is more than or equal to 80%) has a high specific capacity, so that the high-nickel ternary cathode material has a remarkable application prospect in the field of the lithium ion battery with high energy density. However, with the increase of nickel content, the intrinsic crystal structure stability of the material is reduced, the surface chemical activity is aggravated, so that the material faces serious challenges such as rapid cycle life decay, high thermal runaway risk, and processing property degradation caused by surface residual alkali in practical application, which severely restricts the large-scale commercial application process. In view of the above challenges, the prior art explores from multiple dimensions such as material synthesis, bulk doping and surface cladding, for example, the precursor morphology is optimized by a segmented coprecipitation method under an unprotected atmosphere, a multi-element doping strategy is adopted to stabilize the lattice structure, and a dual gradient cladding technology is developed to improve the interface stability. The above techniques all achieve staged results under respective paths, but all focus on the local optimization of a single performance. When the technologies are simply combined to pursue breakthrough of comprehensive performance, the compact surface oxide layer formed by pre-oxidation treatment can seriously obstruct bulk diffusion of subsequent doping ions, so that uneven doping is caused, the heat system required by high-temperature doping sintering is difficult to consider in contradiction with the optimal film forming temperature of medium-temperature cladding treatment, in addition, obvious interface stress can be generated between a core-shell structure and an outer cladding layer due to lattice mismatch, and cracking failure of the cladding layer is easy to be caused. These systematic barriers make it difficult to cooperatively implement the core performance indexes of "high capacity", "long life", and "high safety". Therefore, there is a need for an integrated manufacturing method that can systematically solve the above-mentioned problems, and achieve a synergistic improvement in high capacity, high stability and high safety. Disclosure of Invention The invention overcomes the defects of the prior art and provides a high-capacity high-nickel ternary positive electrode material and a preparation method thereof. In order to achieve the purpose, the technical scheme adopted by the invention is that the high-capacity high-nickel ternary positive electrode material and the preparation method thereof comprise the following steps: S1, adding a nickel-cobalt mixed salt solution, a sodium hydroxide solution and an ammonia water solution into water to prepare a nickel-cobalt binary precursor, adding the nickel-cobalt binary precursor into water, introducing compressed air to perform pre-oxidation treatment, and adding a manganese salt solution and an ammonia water solution into a reaction system to prepare a high nickel ternary precursor with a core-shell structure; S2, carrying out solid-liquid separation, washing and drying on the high-nickel ternary precursor, and carrying out surface reduction heat treatment in a hydrogen/nitrogen mixed atmosphere; S3, mixing the precursor subjected to the surface reduction heat treatment in the step S2 with a doping agent, wherein the doping agent is a compound of a titanium source, an antimony source and a tantalum source; s4, mixing the precursor doped in the step S3 with a lithium source, and performing sectional sintering treatment in an oxygen atmosphere to obtain a high-nickel ternary anode matrix material; S5, dispersing the matrix material in absolute ethyl alcohol to form slurry, adding a mixed coating agent solution consisting of a titanium source solution and an aluminum source solution into the slurry for gradient coating treatment to form an Al-Ti-O gradient coating layer; S6, carrying out solid-liquid separation, washing and drying on the coating product obtained in the step S5, carrying out heat treatment in an oxygen atmosphere, and obtaining the high-capacity high-nickel ternary anode material after crushing, sieving and demagnetizing. In a preferred embodiment of the present invention, in step S1, the nickel salt is selected from at least one of nickel sulfate, nickel nitrate, and nickel acetate, the cobalt salt is selected from at least one of cobalt sulfate, cobalt nitrate, and